Production of shavings from pieces of wood



June 7 M. HIMMELHEBER ET AL 2,796,094

PRODUCTION OF SHAVINGS FROM PIECES OF woon 7 Filed Feb. 16, 1954 2Sheet-Sheet 1 J 1957 M. HIMMELHEBER ET AL 2,796,094

PRODUCTION OF SHAVINGS FROM PIECES OF woon Filed Feb. 16, 1954 2Sheets-Sheet 2 ATTORNEY United States PRODUCTION OF SHAVWGS FROM PECES FWOQD Max Himmelheber, Baiershronn, Black Forest, Klaus Steiner, BadTolz, and Walter Kuii, Frendenstadt, Germany, assignors, by mesneassignments, to Allwood Incorporated, Glarus, Switzerland, a corporationof Our invention relates to the production of flat shavings from piecesof wood, particularly for the manufacture of adhesive-bondedwood-particle panels and similarly composed products.

In the manufacture of such composition products it has been foundpreferable to disintegrate pieces of Wood waste into shavings ofpredetermined and properly chosen properties and dimensions, preferablywith the aid of machinery especially designed for this purpose. Shavingsof a fiat and pliably thin shape are particularly advantageous, and suchshavings have been produced on rotarydisc type shredding machines. Thesemachines, similar to known bark peeling machines, comprise a rotatingdisc equipped with a number of blades whose edges extend alongrespective radii, or at a slight angle thereto, of the disc. The piecesof wood to be disintegrated are previously cut to a given length and arethen placed into a feed box which is traversed against the rotatingblades. A subdivision of the shavings may be obtained by providing themachine with scoring knives rotating together with and ahead of thecutter blades.

In known machines of this type, the blade-carrying disc extends in avertical plane and has a horizontal shaft to permit moving and pressingthe feed box with the properly prepared wood pieces on a horizontal pathtoward the blades. In other machines, particularly for the production ofwood wool, the disc has been given a horizontal arrangement and avertical shaft for the disintegration of pre-shaped pieces of wood. Theproduction of shavings with the aid of the various known slicing orwood-planing methods and devices, however, leaves much to be desired ifthe shavings are to have the characteristics desired for use inhigh-quality composition panels. That is, the known methods and deviceseither fail to sufiiciently secure a substantially uniform size andfavorable fiber orientation of the shavings, or it has been necessary toprovide the feed box or magazine of the machine with clamping orfeed-pressure means that make the replenishment of stock excessivelytime consuming and also result in large residual wood pieces that cannotbe further disintegrated. The necessity of frequently interrupting thedisintegrating operation for replenishment of stock and the large amountof waste make such a production method economically inapplicable forindustrial mass production of wood-shavings panels, aside from the factthat some of the known machines require planing or machining of thestock material prior to the shredding operation.

It is an object of our invention to obviate these deficiencies and toafford producing shavings of the desired characteristics in a continuousoperation and with a complete consumption of stock material that, asidefrom being cut to proper length, need not be prepared by planing or thelike machining.

Another object of the invention is to provide a wood disintegratingmachine that combines the reliability and constructional simplicity of ahorizontal blade-carrying atent O ice cutter disc with stock feedingmeans that secure a continuous feed pressure yet are always freelyaccessible for the supply and replenishment of wood stock.

These and other objects as well as the features of our invention will beapparent from, and will be mentioned in, the following description inconjunction with the embodiments of machines according to the inventionexemplified by the drawings in which:

Fig. l is a partly sectional side elevation and Fig. 2 a top view of ashredder embodying the invention;

Fig. 3 is a sectional detail of the shredder shown in Figs. 1 and 2;

Fig. 4 shows a side elevation of the machine, and

Fig. 5 is a view from the left of Fig. 4.

The machine has a frame structure 21 in which a vertical shaft 22 isjournalled. The shaft carries at its lower end a plane cutter disc 23with a number of radial slots 24 (see Fig. 3). Mounted on the disc 23 ineach slot 24 is a blade support 25. Each support 25 is designed much inthe manner of a bench plane. It has a slot 26 and forms an inclinedmounting surface for a planing blade 27 which is securely fastened tothe support 25 by means of a cover plate 28 and a pressure screw 29.Each support 25 carries ahead of slot 26 a number of scoring knives 30that are equally spaced from each other along the slot 26 in the radialdirection of the disc. Each scoring knife 30 (Fig. 3) is fastened tosupport 25 by a set screw 31.

The upper end of the machine shaft 22 carries a belt sheave 35 driven byan endless belt 36 from a sheave 37 on the shaft of an electric motor 38that is firmly mounted on the frame structure 21. of the machine. Thebelt drive is enclosed within a protective housing 39 (Figs. 1, 2, 4).

The feed box or magazine structure 40 is firmly joined with the frame21. Two opposite vertical sides of'the available magazine space areformed by two endless gripper belts 41, each extending about an upperdrum 42 and a lower drum 43. The two endless belts are driven from anelectric motor 45 (Figs. 1, 4) so that the inner run portions of the twobelts have a downward direction of motion. The motor 45 is connectedwith a pair of pulleys 47 by an endless belt 46. Another endless belt 48connects the pulley pair 47 with a pulley 49 from which the two drums 43are driven through intermediate spur gears shown by dotted lines inFig. 1. The pair of pulleys 47 are enclosed by a housing 48' (Fig. 5),while drive belt 48 and pulley 49 are enclosed by a protective housing49'.

The gripper belts 41 are covered toward the operators place by verticalplates 55, 56 (Fig. 4), and a cross plate 57 (Fig. 4) covers the bottomportion of the magazine space immediately adjacent to the cutter disc.It will be recognized from Fig. 4 that the interior space of the feedbox structure is freely accessible at all times so that stock canreadily be replenished without interruption of the shredding operation,while the downward movement of the belts imposes upon the stock in themagazine space a sufficient feed pressure to always secure a reliableshredding operation even though the magazine space may be filled to onlypart of its capacity. The stock is inserted into the magazine space inthe direction of the arrow 51 in Fig. 2. In the same illustration, thedirection of disc rotation is denoted by an arrow 52. The shavingsproduced by the machine are removed through an opening 53 in the baseportion of the frame structure in the direction of the arrow 54, forinstance, by means of a conveyor belt that passes the shavings to thenext following stage of the panel-producing manufacturing equipment,such as a knife mill (not shown) for splitting the shavings along thegrain into narrower shreds.

The stock to be used in machines according to the invention consists ofelongated and longitudinally fibred pieces or logs. These pieces arefirst cut to a length corresponding to the width of the magazine space.The width of this space, measured along a diameter of the cutter disc,is somewhat shorter than the radial length of the cutter blades. bladepasses horizontally along the bottom opening of the magazine space itslices sequentially along all pieces of stock adjacent to the cutterdisc, and the out has a slanting direction relative to each individualpiece. The wood pieces, placed horizontally into the magazine, may allbe oriented perpendicular to the above-mentioned radial width of themagazine space, the preferred operation, however, requires placing thewood pieces parallel to the radial width of the magazine, as shown inthe illustrated embodiment. With such an orientation of the elongatedwood pieces, the individual cuts of each blade progresses substantiallyacross the grain direction of the stock. However, the shavings slicedoff the stock arelongitudinally fibred and have a length determined bythe radial spacing between the above-mentioned scoring knives. Such acut approximately across the grain direction results in an excellentuniformity in the thickness of the shavings so that the bulk of theshavings shredded from the stock have all a predetermined smallthickness, for instance, of any desired measure between 0.1 and 0.4 mm.Such shavings are sufficiently flat and pliable for good interlacingwhen formed into a mat preparatory to subjecting such a mat tocompression in a panel-molding press. Due to the rigid and well-definedarrangement of the planer-type blades on the disc and the simpleover-all design of the cutting tools, the machines operate with utmostreliability and lend themselves especially for mass production purposesas they afford continuous shredding and complete consumption of thestock material.

It Will be obvious to those skilled in the art, upon a study of thisdisclosure, that the invention permits of various modifications asregards design details and components of the machinery without departingfrom the essential features of our invention and within the scope of theclaim annexed hereto.

We claim:

A machine for shredding longitudinally grained pieces of Wood intopliably thin shavings, comprising a rotatable cutter disc having ahorizontal planar top surface with substantially radial slots and havinga vertical drive shaft, a number of substantially radially extendingcutter blades firmly mounted on said disc in said slots in angularlyspaced relation to each other and having respective cutting edgesprojecting upwardly through said Consequently, when an individual slotsangularly to said horizontal planar top and to above said surface, astationary feed box structure for the reception of elongated wood piecesto be shredded, said box structure being entirely on one side of theaxis of the shaft and extending upwardly from said disc and being opentoward said disc so that said planar top surface forms the bottom of thefeed box space, said box structure having a closed rear wall facing theaxis of said shaft, two conveying devices mounted vertically along theremaining two lateral sides of said feed box structure adjacent to saidrear wall and having a downward direction of motion where said devicesface said feed box space, said devices being engageable with the woodpieces in said space for urging them against said planar disc surface,said feed box structure being open over substantially its entire heightand the entire width of the space which is at the remaining side alongthe periphery of said disc and which is between the two conveyingdevices, to permit replenishing the wood pieces from any height of saidopen side, the radial span of the cutter blades being longer than thelateral dimension of the feed box space measured along the diameter ofthe cutter disc, the feed box being so placed that each cutter blade,when at right angles to the closed rear wall of the box, is offset fromthe center of the space between the two conveying devices, whereby whenlongitudinally fibered wood pieces are pre-cut to a length correspondingto said dimension and are inserted through the said space at theremaining side to orient the wood pieces parallel to the said lateraldimension measured along a cutter disc diameter, the individual cut ofeach blade progresses substantially in a slanting direction across thegrain direction of the pieces, to produce longitudinally fiberedshavings.

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